402 THE SENSORIAL FUNCTIONS. 



ble of receiving; distinct luminous impressions from a class 

 of vibrations which, applied to our visual organs, excite no 

 sensation.* The functions of the antennae, which, though 

 of various forms, are organs universally met with in this class 

 of animals, must be of great importance, though obscurely 

 known; for insects when deprived of them appear to be quite 

 lost and bewildered. 



The Torpedo, tlie Gymnotiis, and several other fishes, 

 arc furnislied with an electrical apparatus, resembling the 

 Voltaic battery, wnich they liave the power of charging and 

 discharging at pleasure. An immense profusion of nerves 

 is distributed upon this organ; and we can hardly doubt that 

 they comniunicate perceptions, with regard to electricity, 

 very different from any that we can feel. In general, in- 

 deed, it may be remarked, that the more an organ of sense 

 differs in its structure from those which we ourselves pos- 

 sess, the more uncertain must be our knowledge of its func- 

 tions. We may, without any great stretch of fancy, conceive 

 ourselves placed in the situation of the beasts of the forest, 

 and comprehend what are the feelings and motives which 

 animate the quadruped and the bird. But how can we 

 transport ourselves, even in imagination, into the dark re- 

 cesses of the ocean, which we know are tenanted by multi- 

 tudinous tribes of fishes, zoophytes, and mollusca? How can 

 we figure to ourselves the sensitive existence of the worm or 

 the insect, organized in so different a manner to ourselves, 

 and occupying so remote a region in the expanse of creation? 

 How can we venture to speculate on the perceptions of the 

 animalcule, whose world is a drop of fluid, and whose fleet- 

 ing existence, chec^uered, perhaps, by various transforma- 

 tions, is destined to run its course in a few hours? 



Confining our inquiries, then, to the more intelligible in- 

 tellectual phenomena displayed by the higher animals, we 

 readily trace a gradation which corresponds with the de- 

 velopment of the central nervous organ, or brain. That the 



• Encyclopjcdiu McUupolilanu, Article *' Ligut." 



